! Tic Tac Clock

Long life on batteries: less than 13µA @ 3 volts, over 5 years on two AAAA batteries or a single CR2450 cell battery.

Very readable.

12/14 hour modes.

Date, leap-year aware.

Daily alarm.

Two extra days-of-the-week alarms.

Count-up timer.

Count-down timer.

Chronometer (stopwatch).

Animations.

User editable messages.

User editable font characters.

Battery voltage display.

Chimes.

Pulses.

Random dice generator.

Tunable crystal frequency drift compensation.

Open source, user manual, utilities.

Fits inside a tic tac® box:

Top

Bottom

Schematic:

All functions on the clock are operated using the single button:

One press displays the time.

Two display the date.

Three display the alarm.

Four display the count-up timer.

Etc...

A long press of the button (one second or mode) enters the settings mode.

Here's a video of the clock being operated to display the time (05:45:24) and then
the date (Sun Jun 22 2014):

N.B.: Crappy webcam that has issues with raster frequency. In person the display is solid.

The choice of a 15 LEDs (3x5) display is to get the most functionality with the least resources.

It can display pretty much all uppercase letters, punctuation and a few other doodles:

The design decisions for this clock are that first and foremost I wanted a small, portable clock that I coulduse on the go. I'm far-sighted (bad eyesight, not clairvoyant) so I need glasses for looking at near things,but I usually walk outside without glasses since I can see just fine past the length of my arms.

This makes it annoying for reading the time on a wristwatch or a phone; it requires pulling out the glasses.

The tic tac clock's large single digit makes it very easy to read without glasses.

Ever since I've owned a digital watch, I've always wished that it had a way to adjust the clock's drift withouthaving to open the blasted thing and adjust a finicky variable capacitor, an endeavour that usually endsup with a much worse drift. The Tic Tac clock lets the user adjust the drift so that very good accuracy can be

accomplished with adjustments as small as parts in 100 million. That's over-kill since the crystal's driftcaused by temperature fluctuations is larger, but 2-3 seconds per month is feasible.

It's using red LEDs because they have lower forward voltage than other colours, so the clock will

last longer on batteries as the voltage drops. Also, red doesn't affect night vision that much, a god-send

for nighttime.

The end goal is to make a wristwatch (SOIC, SMD, etc...) but this prototype is already so useful I've

been carrying it around.

I've chosen a tic tac® box for an enclosure because it's the smallest that fits the components, it's cheap,

and the contents of the box are a bonus. I like tic tac® candy. Lastly, "tic tac" is French for "Tick Tock", soit's very apropos.

By the way, if you'd prefer you can use a 7-segment single digit display module instead, although thecurrent firmware 7-segment code isn't up to date. It will be fixed in a future revision, soon.

Very good accuracy can be achieved with drift measurement and compensation. In this video, two

clocks are running side by side, the one on the left is a breadboard prototype which has had itstime set just a few minutes prior, the one on the right in the orange tictac box had its timeadjusted four days prior. Both are in drift measurement mode which displays pulses everysecond and minute and show better than 1/30th of a second synchronization. That's notbad after four days. The pulses disappear for a short while in the middle of the video because

of the video camera's induced stroboscopic effect.

Here's the content of cheatsheet.txt, if you're curious: (you must be if you're still reading)